(1) Field of the Invention
This invention is in the field of cased telescoped ammunition, and more particularly relates to cased telescoped ammunition rounds in which the projectiles are fin stabilized subcaliber penetrators, with the penetrator of each such round being provided with a sabot which separates from the projectile as the projectile and sabot exit the barrel of the gun from which fired.
(2) Description of Related Art
Cased telescoped ammunition in which the projectile is completely enclosed, or telescoped within the cartridge case, reduces the volume required for a gun, ammunition storage and feed mechanism, or gun system using such ammunition by a significant amount compared with equivalent gun systems using conventionally shaped rounds. The cylindrical shape of cased telescoped cartridges allows for a simpler more reliable and more compact gun system with a higher rate of fire.
In cased telescoped ammunition the projectile is accelerated initially by a booster charge to close, or to obturate, the barrel of the gun before the main propelling charge is ignited. A control tube is commonly used to control the initial movement of the projectile. A booster charge is located in the control tube and is separated by the tube from the main propelling charge. The booster charge is initially confined within the control tube by a booster piston which is attached to the base of the projectile. Main charge ignition does not occur until the advancing piston clears the tube, or exposes or unblocks, ignition ports in the wall of the control tube which, permits products of the burning booster charge to ignite the main charge. Ignition of the main charge is controlled by the position of the projectile. Main propellant ignition occurs when the projectile is at a known and reproducible location in the round and in the barrel of the gun from which it is being fired. Projectile velocity should be at a minimum when main propellant ignition occurs and there should be no venting, blow-by, or pressure leakage of the gases produced by the ignited main propellant as the projectile accelerates down the gun barrel.
Because of the advantages derived from using cased telescoped ammunition rounds, there is a need to develop such a round in which the projectile is a fin stabilized kinetic energy armor penetrating projectile, or penetrator, as such projectiles are commonly used in vehicle mounted gun systems to attack armored vehicles, fixed fortifications, and the like. However, attempting to use a control tube and booster piston which is satisfactory for ejecting spin stabilized projectiles from cased telescoped rounds such as is taught by U.S. Pat. No. 4,604,954 to eject, or launch, fin stabilized penetrators has encountered problems. Fin stabilized kinetic energy penetrators have relatively high length to diameter (L/D) ratios, in the range of from 6.0 to 20.0, with the result that such projectiles cannot accept high loads in the vicinity of the fins in the absence of a substantially uniform force acting over the entire rearward portion of the projectile. Stated another way, a fin stabilized penetrator is not capable of accepting the forces applied to it by conventional cased ammunition without damage to the fins, sabot or penetrator.
Since the control tube and booster piston of conventional cased telescoped ammunition rounds are directly in line with and behind the projectile, their use with fin stabilized projectiles can result in excessively high round lengths.
Attaching the control tube to the rear of a fin stabilized penetrator reduces the stabilizing effect of the fins as well as inhibiting the mounting of a tracer cup in the base of the penetrator so that its trajectory can be visually observed.